Everything below concerns mass spectrometry. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-04-08. Numbers and descriptions here follow the published literature rather than marketing material.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Some nuclear safety agencies make recommendations about the use of thorium mantles and have raised safety concerns regarding their manufacture and disposal; the radiation dose from one mantle is not a serious problem, but that from many mantles gathered together in factories or landfills is.
According to results presented at the 2018 meeting of the American Diabetes Association, Afrezza increases the time that blood glucose levels remain in the optimal range (74–106 mg/dl), reducing both spikes in blood glucose and time in hypoglycemia in adults with type 1 diabetes, compared to insulin aspart.
Lindow Man, also known as Lindow II and (in jest) as Pete Marsh, is the preserved bog body of a man discovered in a peat bog at Lindow Moss near Wilmslow in Cheshire, North West England. The remains were found on 1 August 1984 by commercial peat cutters. Lindow Man is not the only bog body to have been found in the moss; Lindow Woman was discovered the year before, and other body parts have also been recovered. The find was described as "one of the most significant archaeological discoveries of the 1980s" and caused a media sensation. It helped invigorate the study of British bog bodies, which had previously been neglected. Dating the body has proven problematic, but it is thought that he was deposited into Lindow Moss, face down, sometime between 2 BC and 119 AD, in either the Iron Age or Romano-British period. At the time of death, Lindow Man was a healthy male in his mid-20s, and may have been of high social status as his body shows little evidence of having done heavy or rough physical labour during his lifetime. There has been debate over the reason for his death; his death was violent and perhaps ritualistic. The recovered body has been preserved by freeze-drying and is on permanent display at the British Museum, although it occasionally travels to other venues such as the Manchester Museum.
In the 1920s there was an outbreak of a mysterious haemorrhagic cattle disease in Canada and the northern United States. The disease was named sweet clover disease because the cattle had grazed on sweet clover hay. It wasn't until ten years after the outbreak, that a local investigator, Karl P. Link and his student Wilhelm Schoeffel started an intense investigation to find the substance causing the internal bleeding. It took them 6 years to discover dicoumarol, the causing agent. They patented the right for the substance and in 1945 Link started selling a coumarin derivative as a rodenticide. He and his colleagues worked on several variations and ended up with a substance they named warfarin in 1948. It wasn't until 1954 that it was approved for medicinal use in humans making warfarin the first oral anticoagulant drug.
Sources: en.wikipedia.org
nuclear magnetic resonance spectroscopy A technique that exploits the magnetic properties of certain atomic nuclei, useful for identifying unknown compounds. Nuclear magnetic resonance is often abbreviated NMR.
== Importance in winemaking == Assimilable nitrogen is an essential nutrient needed by wine yeast in order to fully complete fermentation with a minimum amount of undesirable by-products (such as compounds like hydrogen sulfide that can create off odors) created. Over the course of a fermentation, yeast may use up to a 1000 mg/L of amino acids though often far less than amount is needed. Yeast can store amino acids in intracellular vacuoles and then later either use them directly, incorporating them into proteins, or break them down and use their carbon and nitrogen components separately. In the absence of nitrogen, yeast will begin to shut down and die off. Some strains will begin breaking down sulfur containing amino acids like cysteine and methionine releasing a sulfur atom that can combine with hydrogen to produce hydrogen sulfide (H2S) which can impart rotten egg odors to the wine. However, there is not a direct correlation between YAN levels and hydrogen sulfide production since H2S can be produced by yeast even in the presence of abundant nitrogen but with instead other vital nutrients (such as the vitamin pantothenic acid) lacking. There are even some strains of S. cerevisiae that produce H2S as a response to having too much available nitrogen (particularly too much glutamic acid and alanine). This is why a prophylactic approach of indiscriminately adding nitrogen supplementation to every fermentation may not have the desired results of preventing H2S.
The bergamot essential oil is particularly subject to adulteration being an essential oil produced in relatively small quantities. Generally adulteration is to "cut" the oil, i.e. adding distilled essences of poor quality and low cost, for example of bitter orange and bergamot mint and/or mixtures of terpenes, natural or synthetic, or "reconstruct" the essence from synthetic chemicals, coloring it with chlorophyll. Worldwide, each year, around three thousand tonnes of declared essence of bergamot are marketed, while the genuine essence of bergamot produced annually amounts to no more than one hundred tons. Natural source analysis based on the Carbon-14 method can identify adulterated essences by detecting synthetic chemicals manufactured from petroleum that are used to mimic the chemical profile of bergamot oil and other essential oils. Gas chromatography with columns having a chiral stationary phase allows analyzing mixtures of enantiomers. The analysis of the enantiomeric distribution of various compounds, such as linalyl acetate and linalool, allows the characterization of the bergamot oil according to the manufacturing process and allows for the detection of possible adulteration. The combined use of isotope ratio mass spectrometry and SNIF-NMR (Site-Specific Natural Isotope Fractionation-Nuclear Magnetic Resonance) allows discovering adulteration otherwise undetectable even allowing for the identification of the geographical origin of the essential oil.
Due to the preference for a cis-amide bond with the preceding residue of C2-substituted pseudoprolines, their incorporation results in a kink conformation of the peptide backbone, thus preventing peptide aggregation, self-association, or β-structure formation.
== Formation mechanism == Eukaryote ribosomes are produced and assembled in the nucleolus. Ribosomal proteins enter the nucleolus and combine with the four rRNA strands to create the two ribosomal subunits (one small and one large) that will make up the completed ribosome. The ribosome units leave the nucleus through the nuclear pores and unite once in the cytoplasm for the purpose of protein synthesis.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.